This change passes all file node ids for clearing to the sqlite storage at once and makes use of ON DELETE CASCADE for
everything else, instead of manally deleting all source locations.
* fixed refreshing to send another ui refresh message after parsing
* keepContent field for MessageBase so that views won't update
* fixed searchmatching to only weigh uppercase letters next to lowercase ones
* fixed file not jumping back to snippets when activating edge
* clicking into empty space deselects active edge
* clear file manager files on every fetch
* added db transaction for file clearing
* use zooming instead of changing font size
Eberhard Graether